Barrier materials having a hydrogen bond, such as polyamide resins, cellulose-based resins, polyvinyl alcohol, and ethylene polyvinyl alcohol, can demonstrate excellent weather resistance and gas barrier properties, which reflect the strength of intermolecular interactions between main chains.
However, in consideration of the use for various industrial products, such barrier resins do not have sufficient flexibility, fatigue resistance, and adhesion to other materials. Such barrier resins have problems in resistance to fatigue and adhesion to rubber, when used, for example, in applications where they are subjected to numerous deformations in a repeated manner on a rubber substrate, typified by tires, and, therefore, attempts have been made to improve these characteristics.
As a technique for improving the flexibility of barrier materials, for example, PTL 1 discloses alternately laminating a layer composed of a barrier material and a flexible elastomer layer to form a multi-layer structure so that gas barrier properties and flexibility are simultaneously achieved.
As a technique for improving the adhesiveness of barrier materials, for example, PTL 2 discloses that a resin composition containing an ethylene vinyl alcohol copolymer, a thermoplastic polyester resin, a thermoplastic resin having a carbon-carbon double bond, and a transition metal salt has improved gas barrier properties and interlayer adhesiveness.